Organochlorines and mercury in Peregrine Falcon eggs from western North Carolina

4 Pages·1998·1.5 MB·English

by  T Augspurger

Sept 1998 Short Communications 251
J Raptor Res. 32(3):251-254
© 1998 The Raptor Research Foundation, Inc.
Organochlorines and Mercury in Peregrine Falcon Eggs from
Western North Carolina
Tom Augspurger
U.S. Fish and Wildlife Service, RO. Box 33726, Raleigh, NC 27636-3726 U.S.A.
Allen Boynton1
North Carolina Wildlife Resources Commission, Nongame and Endangered Wildlife Program,
Morganton, NC 28655 U.S.A.
Key Words: Peregrine Falcon; Falco peregrinus; mercury; Eggs were stored frozen until harvested into acid-rinsed
organochlorinepesticides; North Carolina. and solvent-rinsed glassjars for analyses.
The USFWS Patuxent Analytical Control Facility ana-
lyzed for 20 organochlorine compounds and mercury.
In North Carolina, Peregrine Falcons Falco peregrinus
(
Organochlorine analyses were by gas-liquid chromatog-
anatum) were historically regarded as an uncommon
raphy with peak confirmation of p,p'-DDE by gas chro-
breeding bird in the western mountains (Pearson et al. matography/mass spectrometry under methods adapted
1919, 1942) prior to their contaminant-induced extirpa- from Cromartie et al. (1975). Mercurydeterminationwas
tion in the eastern U.S. (Hickey 1969). Surveys in the performed by cold vapor atomic absorption spectropho-
early 1970s indicated peregrines no longer bred in North tometry as described by theJoint MercuryResidues Panel
Carolina or at any historical nest sites east of the Missis- (1961).
sippi River (Fyfe et al. 1976). Efforts to restore peregrines The lower limit of detection was 0.01 ppm wet weight
to the breeding bird fauna of North Carolina included for organochlorines and 0.04 ppm wet weight for mer-
cury. A procedural blank indicated no background con-
protection of nesting habitat and the introduction of 81
tamination of analytical equipment or reagents. Results
young peregrines, produced in captivityby the Peregrine
of duplicate analyses and spike recoveries for mercury
Fund, Inc. and private breeders (Barclay 1988), at seven DDT
(104%), metabolites (54.7-107%), lindane
sites between 1984-91. Introduced birds first bred in (69.6%), and chlordane metabolites (65.1-89.8%) were
1987 and successfully so in 1988. One to five pairs have within acceptable ranges for method precision and ac-
bred each year producing a mean of 0.0-2.5 young per curacy. Residues reported here were not adjusted for re-
occupied territory and an average of 0.81 young per oc- coveries.
cupied territory from 1987-95 (Boynton and Currie We used a regression equation for American Kestrel
1993, C. McGrath pers. comm.). {Falco sparverius) eggs to estimate egg volume (Wiemeyer
Peregrine Falcons in western North Carolina occupy a et al. 1986). Because samples had dehydrated from ex-
posure and refrigeration, we adjusted all residue concen-
portion ofthe Southern Appalachian recoveryregion; an
trations for moisture loss using egg weight to volume ra-
objective ofthe recovery plan is the establishment of20- tios and assuming a specific gravity of 1.0 (Stickel et al.
25 nesting pairs in this region (U.S. Fish and Wildlife 1973). All contaminant concentrations are reported as
Service [hereafter USFWS] 1979, 1991), a level that has parts per million (ppm) fresh wet weight. Contaminant
not been attained. Although contaminants were not sus- concentrations for the two eggs collected in 1991 from
pected to be limiting productivity, no analyses had been Whiterock Cliff were averaged prior to calculating geo-
performed on this new population prior to this assess- metric means. Consequently, geometric means are based
ment. Our objectives were to quantify organochlorine on clutches {N= 4) rather than individual eggs (N= 5).
and mercury concentrations and shell thickness from Eggshell thicknesses of the five specimens and shell
fragments from four additional nests were determined
western North Carolina peregrine eggs and to evaluate
with a Federal Model 35 bench comparator thickness
their significance relative to reproduction. gauge at the Western Foundation forVertebrate Zoology.
At least 10 measurements of each sample were made for
Methods
each mean reported.
Between 1990-93, five Peregrine Falcon eggs were col-
lected from four clutches in three breeding territories Results and Discussion
after theywere either incubated past term or abandoned.
DDE, a metabolite ofDDT, was considered causative in
the extirpation ofthe Peregrine Falcon after it was found
1 Present address: Virginia Department of Game and In- that DDE-induced eggshell thinning of around 20% was
land Fisheries, Route 1, Box 107, Marion, Virginia 24354 invariably associated with declining populations (Rise-
U.S.A. brough and Peakall 1988). Corresponding DDE residues
)
252 Short Communications Vol. 32, No. 3
Table 1. Concentrations of mercury (Hg) and organochlorines measured in eggs of North Carolina Peregrine
Falcons. Concentrations are ppm fresh wet weight and corresponding shell thicknesses are in mm.
Shell Total Total
P-P'
Location and Year Thickness Hg DDE DDTa CHLORDANEb Dieldrin Lindane
Chimney Rock 0.332 0.14 1.47 1.70 0.50 0.12 0.02
Rutherford County
1993
Looking Glass Rock 0.329 0.07 5.72 6.13 1.95 0.42 0.03
Transylvania County
1990
Looking Glass Rock 0.386 0.11 3.96 4.26 1.04 0.18 0.01
Transylvania County
1992
Whiterock Cliff 0.328 0.05 5.14 5.70 1.32 0.54 0.02
Madison County
1991
Whiterock Cliff 0.321 0.10 2.64 3.03 1.71 0.66 0.01
Madison County
1991
a Total DDT defined here as summed o,p'—DDD, o,p'—DDE, o,p'-DDT, p,p'-DDD, p,p'—DDE, and p,p'—DDT.
bTotal chlordane defined here as sum ofalpha chlordane, cis-nonachlor, gamma chlordane, heptachlor epoxide, oxychlordane, and
trans-nonachlor.
of 15-20 ppm have been associated with population level >1.5 ppm heptachlor epoxide to be critical for produc-
average eggshell thinning ofthis magnitude (Peakall and ing adverse effects in peregrine eggs.
Kiff 1988). The geometric mean concentration of p,p'- Dieldrin levels in raptors were reviewed by Peakall et
DDE in North Carolina Peregrine Falcon clutches was al. (1990); they derived an egg screening value for deter-
3.37 ppm (Table 1). Total metabolites of DDT ranged mining adverse effects in Peregrine Falcons of 1-4 ppm.
from 1.70-6.13 ppm with a geometric mean concentra- Peakall (1996) reported a “no-observed-effect” level of
tion of 3.73 ppm. These DDE concentrations are well dieldrin at 0.7 ppm. North Carolina Peregrine Falcon
below those associated with population declines (Peakall eggs were well below this range with a geometric mean
and Kiff 1988). of 0.27 ppm.
mm
Arithmetic mean eggshell thicknesses were 0.339 Lindane has been used to control balsam wooly adel-
mm
for the five whole eggs and 0.334 when the shell gid (Adelges piceae infestation of fraser fir (Abiesfraseri)
fragments from four additional nests were included. As- in western North Carolina. The geometric mean concen-
suming a pre-1947 eggshell thickness for eastern Pere- tration of lindane in our samples was 0.02 ppm. Lindane
mm
grine Falcons of0.360 (Burns et al. 1994), the values has not been associated with avian impairment in the
reported here are approximately 7% thinner than nor- wild, and levels well above those reported here have been
mal, pre-DDT era eggshells. Peakall and Kiffs (1988) detected in bird eggs without any apparent effects (Wie-
summary of thinning data indicate that extirpated or de- meyer 1996).
clining Peregrine Falcon populations occurred whenever Mercury has been shown to cause mortality and repro-
mean population-level eggshell thinning exceeded 17% ductive impairment in wild birds (Eisler 1987). The geo-
(except for intensively managed populations). Fyfe et al. metric mean mercury concentration of 0.10 ppm in
(1988) suggested 14.5% thinning as a minimum estimate North Carolina Peregrine Falcon eggs is below estimates
of the threshold below which there is no appreciable ef- of 0.5—1.0 ppm used by others as screening values for
fect on peregrine productivity. Since the stock for the reproductive effects on peregrines (Peakall et al. 1990)
restored eastern Peregrine Falcon population was de- and other raptors (Bowerman et al. 1995).
rived from several sources, eggshell thickness compari- The geometric mean concentration of DDE in pere-
sons must necessarily be approximate. grine eggs from the Southern Appalachian recovery re-
The geometric mean concentration of total chlordane gion was approximately half that reported for eggs from
components and metabolites (1.11 ppm) was composed the mid-Atlantic and northeastern U.S. (Gilroy and Bar-
primarily by oxychlordane (0.30 ppm) and heptachlor clay 1988, Burns et al. 1994). The lower DDE concentra-
epoxide (0.22 ppm). Peakall et al. (1990) considered tions in peregrine eggs from the Southern Appalachian
Sept 1998 Short Communications 253
recovery region may be due to different prey prefer- Burns, S.A., W.M. Jarman, T.J. Cade, L.F. Kiff and BJ
ences. Preliminary data indicate that western North Car- WALTON. 1994. Organochlorines and eggshell thin-
olina peregrines depend largely on resident birds, partic- ning in Peregrine Falcon Falco peregrinus eggs from
ularly Rock Doves (Columba livid) Mourning Doves the eastern United States, 1986-1988. Pages 709-716
,
(Zenaida macroura), Northern Flickers (Colaptes auratus), in B.-U. Meyburg and R.D. Chancellor [Eds.], Raptor
and Blue Jays (Cyanocitta cristata) (Boynton and Currie conservation today. Proceedings of the IV world con-
1993). Additional documentation of prey preferences is ference on birds ofprey and owls. Pica Press, London,
ongoing. U.K.
Factors possibly limiting productivity include nest pre- Cromartie, E., W.L. Reichel, L.N. Locke, A.A. Belisle,
dation, inclement weather, inexperience, poor food sup- T.E. Kaiser, T.G. Lamont, B.M. Mulhern, R.M. Prou-
ply, and human disturbance (Boynton and Currie 1993). ty and D.M, Swineford. 1975. Residues of organo-
While a larger data set is advisable before ruling out pol- chlorine pesticides and polychlorinatedbiphenyls and
lutant effects, our current data suggest that environmen- autopsy data for Bald Eagles, 1971-72. Pest. Momt
J.
tal contaminants are not limiting productivity of pere- 9:11-14.
grines in the Southern Appalachian recovery region. The Eisler, R. 1987. Mercury hazards to fish, wildlife, and
USFWS (1995) has indicated its intention to remove the invertebrates: a synoptic review. USFWS Biol. Rep.
MD
Peregrine Falcon from the list of Endangered and 85(1.10). U.S. Fish Wildl. Serv., Laurel, U.S.A
Threatened Species. These data may serve as a baseline Fyfe, R.W., S.A. Temple and T.J. Cade. 1976. The 1975
in future monitoring of the Southern Appalachian pop- North American Peregrine Falcon survey. Can. Field
ulation which may be a requirement following delisting. Nat. 90:228-273.
R.W. Risebrough,J.G. Monk, W.M.Jarman, D.W.
— ,
Resumen. Concentraciones de pesticidas organoclora- Anderson, L.F. Kiff, J.L. Linger, I.C.T. Nisbet, W.
dos y mercurio fueron encontrados en huevos colectados Walker, II and B.J. Walton. 1988. DDE, productivity,
de cinco halcones peregrinos de una poblacion reesta- and eggshell thickness relationships in the genus Fal-
blecida en el noroeste de Carolina. Las concentraciones co. Pages 319-335 in T.J. Cade, J.H. Enderson, C.G.
de la media geometrica de p,p' DDE (3.37 ppm en peso Thelander and C.M. White [Eds.], Peregrine Falcon
fresco), total de metabolitos de chlordane (1.11 ppm), populations: their management and recovery. The
dieldrin (0.27 ppm), lindano (0.02 ppm), y mercurio Peregrine Fund, Inc., Boise, ID U.S.A.
(0.10 ppm) estaban generalmente por debajo de los ni- Gilroy, M.J. and J.H. Barclay. 1988. DDE residues and
veles asociados al fracaso reproductive. Los 0.334 mili- eggshell characteristics of reestablished peregrines in
metros de la media aritmetica del grueso de la cascara the eastern United States. Pages 403-411 mT.J. Cade,
de los huevos, fue del 7% mas delgada de lo normal J.H. Enderson, C.G. Thelander and C.M. White
encontrado en la “pr-era” del DDT de la poblacion orig- [Eds.], Peregrine Falcon populations: their manage-
inal del este de Estados Unidos. ment and recovery. The Peregrine Fund, Inc., Boise
[Traduccion de Cesar Marquez] ID U.S.A.
Hickey, 1969. Peregrine Falcon populations: their bi-
Acknowledgments J.J.
ology and decline. Univ. Wisconsin Press, Madison,
We thankJohn Moore of Patuxent Analytical Control WI U.S.A.
Facility for coordinating chemical analyses. The data Joint Mercury Residue Panel. 1961. Recommended
were part ofUSFWS Regional Study ID#93-4PER. Stanley
Wiemeyer, Chuck Henny, Tom Cade, Robert Currie, methods of analysis of pesticide residues in food
Chris McGrath, and Randy Wilson provided helpful re- stuffs. Analyst 86:608-614.
views of earlier versions of the manuscript. Peakall, D.B. 1996. Dieldrin and other cyclodiene pes-
ticides in wildlife. Pages 73-97 in W.N. Beyer, G.H.
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© 1998 The Raptor Research Foundation, Inc.
Importance of Birds and Potential Bias in Food Habit Studies of
Montagu’s Harriers (Circuspygargus) in Southeastern Spain
Jose A. SAnchez-Zapata and Jose F. Calvo
Departamento de Ecologia e Hidrologia, Facultad Biologia, Universidad de Murcia,
Campus de Espinardo, 30100Espinardo, Murcia, Spain
Key Words: Montagu’s Harrier, Circus pygargus; diet, small birds and mammals are important preyin northern
mediterranean. and central Europe, whereas in southern Europe inver-
tebrates appear to be numerically important, together
Methods used to study the diets of raptors include the with small birds (Underhill-Day 1993, Hiraldo et al.
analysis of pellets, stomach contents, prey remains in 1975). The goal ofour studywas to assess the importance
nests or under perches, and direct observation of prey ofbirds in the diet ofMontagu’s Harriers and to test how
delivered to nests. In many species, including harriers different study methods affect the results of such a food
Circus spp.), analysis of prey remains only appears to habits study.
(
underestimate the proportion of smaller prey and over-
StudyArea and Methods
estimate the occcurence of large prey (Schipper 1973,
Simmons et al. 1991, Manosa 1994, Real 1996). Several The diets of three pairs of Montagu’s Harriers breed-
researchers have studied the diet of Montagu’s Harrier ing in a wadi or “rambla” in a mediterranean semiarid
{Circuspygargus) during the breeding season (Perez-Chis- region in southeastern Spain (Suarez et al. 1996) were
cano and Fernandez-Cruz 1971, Perez-Chiscano 1974, studied during 1995. Ajauque is a small wetland located
in the most arid sector (average annual rainfall = 30 cm)
Corbacho et al. 1995, Thiollay 1968, Helmich 1986), on
of Murcia in southeastern Spain. Ajauque rambla drains
migration (Castroviejo 1969), and while wintering
an impermeable watershed ofsedimentary marls. In arid
(Cramp and Simmons 1980, Cormier and Baillon 1991). and semiarid lands of the region, ramblas are more pro-
Extensive studies of their breeding diet in Spain (Hiraldo ductive than surrounding lands owing to theirvegetation
et al. 1975, Arroyo 1997), Holland and France (Schipper that consists mainlyofreeds {Phragmites australis) andhal-
1973), and Britain (Underhill-Day 1993) indicate that ophytic plants. The Ajauque rambla is part ofa protected